1. Field of the Invention
The present invention relates to a liquid pressure control system including a spool-type control valve mounted between a liquid pressure source and an actuator so that an output liquid pressure from the liquid pressure source can be controlled in accordance with a thrust exhibited by a linear solenoid.
2. Description of the Related Art
A conventional liquid pressure control system is already known, for example, from Japanese Patent Application Laid-open No. 5-324092 and the like.
The conventional liquid pressure control system is required to avoid a situation where the supply of a liquid pressure to the actuator is disenabled due to the malfunction of the linear solenoid. In the conventional system, another solenoid is disposed in an axial arrangement with the linear solenoid so that, when the linear solenoid is malfunctioned, the supply of the liquid pressure to the actuator is secured by forcibly operating the control valve by another solenoid.
The conventional system has a structure in which the linear solenoid and the another solenoid are disposed in the axial arrangement, and hence the size of the liquid pressure control system is increased in the axial direction of the spool-type control valve. In addition, when a spool of the control valve is locked within a valve housing to block the communication between a liquid pressure source and the actuator by the spool, the supply of the liquid pressure cannot be secured in the conventional system.